Get the existing-merchants verification check summary and the list of matched merchants for a merchant. Returns a check object (verificationType, query, scanResult, merchantApplicationRequirement, verificationResult) and a merchants array (mid, dba, ssn, taxId, phones, email, dda, dbaAddress, status, statusDate). When the check has not been run, check is null and merchants is an empty array. When the check has run but no matches were found, check is populated and merchants is an empty array. SSN, TaxId, and DDA are masked. Requires the AllowDisplayExistingMerchantsReview role option.